1. Field
Exemplary embodiments of the present invention relate to semiconductor design technology, and more particularly, to a negative voltage regulation circuit and a voltage generation circuit including the same.
2. Description of the Related Art
Semiconductor devices operate internal circuits thereof using external voltages supplied from the external source. However, since various levels of voltages are used in a semiconductor device, it may be difficult to supply all of the voltages to be used in the semiconductor device from the external source. In this regard, a semiconductor device includes voltage generation circuits for generating voltages with various levels using the external voltages.
FIG. 1 is a block diagram illustrating a conventional voltage generation circuit for generating a read voltage supplied to a word line in a read operation in a nonvolatile memory device such as a flash memory.
Referring to FIG. 1, the voltage generation circuit includes a first correction unit 110, a second correction unit 120, a target value provision unit 130, and an adding unit 140.
The first correction unit 110 generates a voltage X for regulating the level of the read voltage VREAD which is a final output voltage of the voltage generation circuit, based on a process skew variation. That is, the level of the voltage X is changed based on the process skew variation.
The second correction unit 120 for correcting a temperature variation generates a voltage Y based on the voltage X and temperature information (not illustrated) outputted from a temperature sensor (not illustrated). That is, the level of the voltage Y is changed based on the level of the voltage X and the temperature information. Thus, the voltage Y includes information on the amount of the read voltage VREAD to be regulated based on the process skew variation and the temperature variation.
The target value provision unit 130 generates a voltage Z having information on a target voltage of the read voltage VREAD. The target voltage indicates a voltage level of the read voltage VREAD in a state in which the process skew variation and the temperature variation are normal. For example, when the target voltage is 2V, the read voltage VREAD becomes 2±αV based on the process skew variation and the temperature variation (α is a correction value corresponding to the process skew variation and the temperature variation). When the target voltage is 3V, the read voltage VREAD becomes 3±αV based on the process skew variation and the temperature variation.
The adding unit 140 linearly adds the voltage Y and the voltage Z to generate the read voltage VREAD. Since the voltage Y includes information on a correction value of the read voltage VREAD based on the temperature variation and the process skew variation and the voltage Z includes information on the target voltage of the read voltage VREAD, the read voltage VREAD generated by linearly adding the voltage Y and the voltage Z has a value of ‘target voltage±α’.
In the conventional art, only a positive voltage is used as the read voltage VREAD. Recently, a negative voltage is also used as the read voltage to secure cell Vt distribution. However, it may be difficult to design the adding unit 140 that adds a negative voltage (e.g., the target voltage) and a positive voltage (e.g., the correction value of the target voltage) or adds two negative voltages. Since the adding unit 140 uses the negative voltage as a driving voltage even when implemented, a large amount of current may be consumed. In this regard, a voltage generation circuit that may regulate the level of a negative voltage by positive voltages while providing the negative voltage as a final output voltage is in demand.